What is Forensic Osteology What is Forensic Osteology? The simplest definition of Forensic Osteology is that it is the application of the study of bones (osteology) to the field of forensic science. Whereas a Medical Examiner (aka - ME, and usually a trained forensic pathologist) is experienced in dealing with bodies that still retain soft tissues, the field of forensic osteology deals almost exclusively with skeletal material, and the manner in which the skeletonization occurred. On a comparative note - Forensic Anthropology adds to the field of osteology by combining archaeological field techniques with the area of skeletal anatomy. A more detailed description of forensic anthropology can be seen at the website for the American Board of Forensic Anthropology . France Casting Anatomical background For the 2-day Forensic Osteology workshops, it is assumed that all participants will have a fundamental understanding and working knowledge of human anatomy, especially skeletal anatomy, i.e., you should be able to at least identify all of the major bones and landmarks of the human skeleton. The structure list for 2-day workshops can be accessed by clicking the following link: Osteology List For those not possessing such a background - all is not lost.

Some excellent anatomy sites are located at the following URLs: A few hours time at the above sites should bring most of the non-anatomists "up to speed" as far as the anatomy and terminology are concerned. The following texts are quite useful for reference: Human Osteology, by William M. Bass (ISBN: 0-943414-81-4) The Human Bone Manual, by Tim D. White & Pieter A Folkens (ISBN: 0-12-088467-4) Introduction to Forensic Anthropology - A Textbook, by Steven N. Byers (ISBN: 0-205-43538-6) Forensic Osteology - Advances in the Identification of Human Remains, (2nd ed.) edited by Kathleen J. Reichs (ISBN: 0-398-06804-6) Additional/alternative workshops As previously mentioned, this is a course designed for those needing introductory-level exposure to forensic osteology.

Those already possessing a significant working knowledge of forensic science and forensic osteology/anthropology would be best served by taking one of the more in-depth forensic anthropology "short courses" offered at various colleges and universities around the country. I can highly recommend any of the NSF-sponsored Chautauqua short courses, as well as any of the summer short courses offered through the Mercyhurst Archaeological Institute at Mercyhurst College , Erie, PA. The facilities and the faculty are some of the best you will ever encounter! Please note that Mercyhurst also offers a Master of Science degree in Forensic and Biological Anthropology. Baccalaureate students considering an MS degree in the field of forensic anthropology, or a related area, should certainly investigate the program at Mercyhurst. Additional workshops are offered through the Anthropology Department at the University of Tennessee - Knoxville, and these often include time spent at the "Body Farm" (Anthropology Research Facility). The faculty & staff at UT-K are absolutely stellar! I have also attended the AFIP/NTSB short course, and it is well worth attending as well!.

( Armed Forces Institute of Pathology ) While it does not go into the depth that the Mercyhurst or UT-K workshops do, it provides an excellent introduction into all aspects of forensic anthropology. A logical plan would be to attend the AFIP course one year, followed by some of the Mercyhurst and/or UT-K courses each of the following Summers. TENTATIVE TOPICS FOR 2-DAY WORKSHOP Link to Announcement Page - for participants who have already registered. While the main thrust of the workshop is Forensic Osteology, several other relevant areas will be touched on in the 2-day workshops. A significant number of the specimens used for the hands-on lab sessions will be real human bones. The remainder are high quality replica castings. Basic Taphonomy (lecture) - Taphonomy deals with the various processes that lead to the skeletonization of a body. This portion of the workshop will include discussions of post-mortem changes, mummification, submerged & buried bodies, contemporary vs archaeological specimens, and environmental factors influencing skeletonization. Ballistic & Sharp Trauma (lecture with hands-on lab session) - In this part of the workshop, participants will be exposed to the physical aspects of ballistic and sharp trauma of bone.

The concept of sawmark identification will also be covered. PMI/TOD (lecture) - Estimation of Post Mortem Interval and Time of Death. Skeletal Inventory(lecture & lab) - Determining the number and condition of bones found at a forensic scene. MNI (lecture with hands-on lab session*) - Determination of Minimum Number of Individuals in cases involving multiple decedents. Reconstruction of a human hand recovered from fire. Identification of human skeletal remains/Biological Profile - (lecture & lab). Determination of class characteristics, i.e., sex, stature, age, and race/ancestry. Human vs non-human remains. Introductory forensic odontology. Inventory & Identification of calcined human bone from fire. Bone warpage due to exposure to elevated temperature. Burned human femur fragment. Odontology component includes tooth identification, age & racial differences, as well as postmortem vs. premortem tooth loss. What can this tooth tell us about the original owner??? What can be determined from this specimen? Age, sex, pre vs. postmortem tooth loss? Fetal skeletal inventory & MNI determination lab (before I & R) This "trophy skull" specimen was found in a dumpster behind an abandoned store.

We often use it as one of the Case Studies for the workshop. Preparation of teaching specimens (lecture & demo. Presented only for those workshops where all participants are educators.) - This final portion of the course involves an introduction to the hows & whys of obtaining specimens, as well as altering replica specimens and animal bones so as to make them appear as authentic forensic specimens. Suggestions for hands-on labs will also be provided, e.g., a forensic exhumation lab. Finally - we will have a discussion for those who are interested in starting a forensic science course at their school. Participants of June 2006 Workshop Participants of November 2006 Workshop Instructor Profile II. Osteology. 1. Development of the Skeleton. Gray, Henry. 1918. Anatomy of the Human Body. Total 206 The patellæ are included in this enumeration, but the smaller sesamoid bones are not reckoned. 3 Bones are divisible into four classes: Long, Short, Flat, and Irregular. 4 Long Bones.The long bones are found in the limbs, and each consists of a body or shaft and two extremities.

The body, or diaphysis is cylindrical, with a central cavity termed the medullary canal; the wall consists of dense, compact tissue of considerable thickness in the middle part of the body, but becoming thinner toward the extremities; within the medullary canal is some cancellous tissue, scanty in the middle of the body but greater in amount toward the ends. The extremities are generally expanded, for the purposes of articulation and to afford broad surfaces for muscular attachment. They are usually developed from separate centers of ossification termed epiphyses, and consist of cancellous tissue surrounded by thin compact bone. The medullary canal and the spaces in the cancellous tissue are filled with marrow. The long bones are not straight, but curved, the curve generally taking place in two planes, thus affording greater strength to the bone. The bones belonging to this class are: the clavicle, humerus, radius, ulna, femur, tibia, fibula, metacarpals, metatarsals, and phalanges.

5 Short Bones.Where a part of the skeleton is intended for strength and compactness combined with limited movement, it is constructed of a number of short bones, as in the carpus and tarsus. These consist of cancellous tissue covered by a thin crust of compact substance. The patellæ, together with the other sesamoid bones, are by some regarded as short bones. 6 Flat Bones.Where the principal requirement is either extensive protection or the provision of broad surfaces for muscular attachment, the bones are expanded into broad, flat plates, as in the skull and the scapula. These bones are composed of two thin layers of compact tissue enclosing between them a variable quantity of cancellous tissue. In the cranial bones, the layers of compact tissue are familiarly known as the tables of the skull; the outer one is thick and tough; the inner is thin, dense, and brittle, and hence is termed the vitreous table. The intervening cancellous tissue is called the diploë, and this, in certain regions of the skull, becomes absorbed so as to leave spaces filled with air (air-sinuses) between the two tables.

The flat bones are: the occipital, parietal, frontal, nasal, lacrimal, vomer, scapula, os coxæ (hip bone), sternum, ribs, and, according to some, the patella. 7 Irregular Bones.The irregular bones are such as, from their peculiar form, cannot be grouped under the preceding heads. They consist of cancellous tissue enclosed within a thin layer of compact bone. The irregular bones are: the vertebræ, sacrum, coccyx, temporal, sphenoid, ethmoid, zygomatic, maxilla, mandible, palatine, inferior nasal concha, and hyoid. 8 Surfaces of Bones.If the surface of a bone be examined, certain eminences and depressions are seen. These eminences and depressions are of two kinds: articular and non-articular. Well-marked examples of articular eminences are found in the heads of the humerus and femur; and of articular depressions in the glenoid cavity of the scapula, and the acetabulum of the hip bone. Non-articular eminences are designated according to their form.

Thus, a broad, rough, uneven elevation is called a tuberosity, protuberance, or process, a small, rough prominence, a tubercle; a sharp, slender pointed eminence, a spine; a narrow, rough elevation, running some way along the surface, a ridge, crest, or line. Non-articular depressions are also of variable form, and are described as fossæ, pits, depressions, grooves, furrows, fissures, notches, etc. These non-articular eminences and depressions serve to increase the extent of surface for the attachment of ligaments and muscles, and are usually well-marked in proportion to the muscularity of the subject. A short perforation is called a foramen, a longer passage a canal. 9 1. Development of the Skeleton The Skeleton.The skeleton is of mesodermal origin, and may be divided into (a) that of the trunk (axial skeleton), comprising the vertebral column, skull, ribs, and sternum, and (b) that of the limbs (appendicular skeleton). 10 The Vertebral Column.The notochord (Fig.

19) is a temporary structure and forms a central axis, around which the segments of the vertebral column are developed. 11 It is derived from the entoderm, and consists of a rod of cells, which lies on the ventral aspect of the neural tube and reaches from the anterior end of the mid-brain to the extremity of the tail. On either side of it is a column of paraxial mesoderm which becomes subdivided into a number of more or less cubical segments, the primitive segments ( Figs. 19 and 20 ). These are separated from one another by intersegmental septa and are arranged symmetrically on either side of the neural tube and notochord: to every segment a spinal nerve is distributed. At first each segment contains a central cavity, the myocl, but this is soon filled with a core of angular and spindle-shaped cells. The cells of the segment become differentiated into three groups, which form respectively the cutis-plate or dermatome, the muscle-plate or myotome, and the sclerotome (Fig. 64 ).

The cutis-plate is placed on the lateral and dorsal aspect of the myocl, and from it the true skin of the corresponding segment is derived; the muscle-plate is situated on the medial side of the cutis-plate and furnishes the muscles of the segment. The cells of the sclerotome are largely derived from those forming the core of the myocl, and lie next the notochord. Fusion of the individual sclerotomes in an antero-posterior direction soon takes place, and thus a continuous strand of cells, the sclerotogenous layer, is formed along the ventro-lateral aspects of the neural tube. The cells of this layer proliferate rapidly, and extending medialward surround the notochord; at the same time they grow backward on the lateral aspects of the neural tube and eventually surround it, and thus the notochord and neural tube are enveloped by a continuous sheath of mesoderm, which is termed the membranous vertebral column. In this mesoderm the original segments are still distinguishable, but each is now differentiated into two portions, an anterior, consisting of loosely arranged cells, and a posterior, of more condensed tissue (Fig.

65, A and B ). Between the two portions the rudiment of the intervertebral fibrocartilage is laid down (Fig. 65, C ). Cells from the posterior mass grow into the intervals between the myotomes (Fig. 65, B and C) of the corresponding and succeeding segments, and extend both dorsally and ventrally; the dorsal extensions surround the neural tube and represent the future vertebral arch, while the ventral extend into the body-wall as the costal processes. The hinder part of the posterior mass joins the anterior mass of the succeeding segment to form the vertebral body. Each vertebral body is therefore a composite of two segments, being formed from the posterior portion of one segment and the anterior part of that immediately behind it. The vertebral and costal arches are derivatives of the posterior part of the segment in front of the intersegmental septum with which they are associated. 11 FIG. 64 Transverse section of a human embryo of the third week to show the differentiation of the primitive segment. (Kollmann.) ao. Aorta. m.p. Muscle-plate. n.c. Neural canal. sc. Sclerotome. s.p.

cutis-plate. ( See enlarged image ) FIG. 65 Scheme showing the manner in which each vertebral centrum is developed from portions of two adjacent segments. ( See enlarged image ) This stage is succeeded by that of the cartilaginous vertebral column. In the fourth week two cartilaginous centers make their appearance, one on either side of the notochord; these extend around the notochord and form the body of the cartilaginous vertebra. A second pair of cartilaginous foci appear in the lateral parts of the vertebral bow, and grow backward on either side of the neural tube to form the cartilaginous vertebral arch, and a separate cartilaginous center appears for each costal process. By the eighth week the cartilaginous arch has fused with the body, and in the fourth month the two halves of the arch are joined on the dorsal aspect of the neural tube. The spinous process is developed from the junction of the two halves of the vertebral arch. The transverse process grows out from the vertebral arch behind the costal process.

12 In the upper cervical vertebræ a band of mesodermal tissue connects the ends of the vertebral arches across the ventral surfaces of the intervertebral fibrocartilages. This is termed the hypochordal bar or brace; in all except the first it is transitory and disappears by fusing with the fibrocartilages. In the atlas, however, the entire bow persists and undergoes chondrification; it develops into the anterior arch of the bone, while the cartilage representing the body of the atlas forms the dens or odontoid process which fuses with the body of the second cervical vertebra. 13 FIG. 66 Sagittal section through an intervertebral fibrocartilage and adjacent parts of two vertebræ of an advanced sheeps embryo. (Kölliker.) ( See enlarged image ) The portions of the notochord which are surrounded by the bodies of the vertebræ atrophy, and ultimately disappear, while those which lie in the centers of the intervertebral fibrocartilages undergo enlargement, and persist throughout life as the central nucleus pulposus of the fibrocartilages (Fig. 66 ).

14 The Ribs.The ribs are formed from the ventral or costal processes of the primitive vertebral bows, the processes extending between the muscle-plates. In the thoracic region of the vertebral column the costal processes grow lateralward to form a series of arches, the primitive costal arches. As already described, the transverse process grows out behind the vertebral end of each arch. It is at first connected to the costal process by continuous mesoderm, but this becomes differentiated later to form the costotransverse ligament; between the costal process and the tip of the transverse process the costotransverse joint is formed by absorption. The costal process becomes separated from the vertebral bow by the development of the costocentral joint. In the cervical vertebr (Fig. 67) the transverse process forms the posterior boundary of the foramen transversarium, while the costal process corresponding to the head and neck of the rib fuses with the body of the vertebra, and forms the antero-lateral boundary of the foramen.

The distal portions of the primitive costal arches remain undeveloped; occasionally the arch of the seventh cervical vertebra undergoes greater development, and by the formation of costovertebral joints is separated off as a rib. In the lumbar region the distal portions of the primitive costal arches fail; the proximal portions fuse with the transverse processes to form the transverse processes of descriptive anatomy. Occasionally a movable rib is developed in connection with the first lumbar vertebra. In the sacral region costal processes are developed only in connection with the upper three, or it may be four, vertebræ the processes of adjacent segments fuse with one another to form the lateral parts of the sacrum. The coccygeal vertebr are devoid of costal processes. 15 FIG. 67 Diagrams showing the portions of the adult vertebræ derived respectively from the bodies, vertebral arches, and costal processes of the embryonic vertebræ. The bodies are represented in yellow, the vertebral arches in red, and the costal processes in blue.

( See enlarged image ) The Sternum.The ventral ends of the ribs become united to one another by a longitudinal bar termed the sternal plate, and opposite the first seven pairs of ribs these sternal plates fuse in the middle line to form the manubrium and body of the sternum. The xiphoid process is formed by a backward extension of the sternal plates. 16 The Skull.Up to a certain stage the development of the skull corresponds with that of the vertebral column; but it is modified later in association with the expansion of the brain-vesicles, the formation of the organs of smell, sight, and hearing, and the development of the mouth and pharynx. 17 The notochord extends as far forward as the anterior end of the mid-brain, and becomes partly surrounded by mesoderm (Fig. 68 ). The posterior part of this mesodermal investment corresponds with the basilar part of the occipital bone, and shows a subdivision into four segments, which are separated by the roots of the hypoglossal nerve.

The mesoderm then extends over the brain-vesicles, and thus the entire brain is enclosed by a mesodermal investment, which is termed the membranous cranium. From the inner layer of this the bones of the skull and the membranes of the brain are developed; from the outer layer the muscles, bloodvessels, true skin, and subcutaneous tissues of the scalp. In the shark and dog-fish this membranous cranium undergoes complete chondrification, and forms the cartilaginous skull or chondrocranium of these animals. In mammals, on the other hand, the process of chondrification is limited to the base of the skullthe roof and sides being covered in by membrane. Thus the bones of the base of the skull are preceded by cartilage, those of the roof and sides by membrane. The posterior part of the base of the skull is developed around the notochord, and exhibits a segmented condition analogous to that of the vertebral column, while the anterior part arises in front of the notochord and shows no regular segmentation.

The base of the skull may therefore be divided into (a) a chordal or vertebral, and (b) a prechordal or prevertebral portion. 18 FIG. 68 Sagittal section of cephalic end of notochord. (Keibel.) ( See enlarged image ) FIG. 69 Diagrams of the cartilaginous cranium. (Wiedersheim.) ( See enlarged image ) In the lower vertebrates two pairs of cartilages are developed, viz., a pair of parachordal cartilages, one on either side of the notochord; and a pair of prechordal cartilages, the trabeculæ cranii, in front of the notochord (Fig. 66 ). The parachordal cartilages (Fig. 69) unite to form a basilar plate, from which the cartilaginous part of the occipital bone and the basi-sphenoid are developed. On the lateral aspects of the parachordal cartilages the auditory vesicles are situated, and the mesoderm enclosing them is soon converted into cartilage, forming the cartilaginous ear-capsules.

These cartilaginous ear-capsules, which are of an oval shape, fuse with the sides of the basilar plate, and from them arise the petrous and mastoid portions of the temporal bones. The trabeculæ cranii (Fig. 69) are two curved bars of cartilage which embrace the hypophysis cerebri; their posterior ends soon unite with the basilar plate, while their anterior ends join to form the ethmoidal plate, which extends forward between the fore-brain and the olfactory pits. Later the trabeculæ meet and fuse below the hypophysis, forming the floor of the fossa hypophyseos and so cutting off the anterior lobe of the hypophysis from the stomodeum. The median part of the ethmoidal plate forms the bony and cartilaginous parts of the nasal septum. From the lateral margins of the trabeculæ cranii three processes grow out on either side.

The anterior forms the ethmoidal labyrinth and the lateral and alar cartilages of the nose; the middle gives rise to the small wing of the sphenoid, while from the posterior the great wing and lateral pterygoid plate of the sphenoid are developed ( Figs. 70, 71 ). The bones of the vault are of membranous formation, and are termed dermal or covering bones. They are partly developed from the mesoderm of the membranous cranium, and partly from that which lies outside the entoderm of the foregut. They comprise the upper part of the occipital squama (interparietal), the squamæ and tympanic parts of the temporals, the parietals, the frontal, the vomer, the medial pterygoid plates, and the bones of the face. Some of them remain distinct throughout life, e.g., parietal and frontal, while others join with the bones of the chondrocranium, e.g., interparietal, squamæ of temporals, and medial pterygoid plates. 19 FIG.

70 Model of the chondrocranium of a human embryo, 8 cm. long. (Hertwig.) The membrane bones are not represented. ( See enlarged image ) Recent observations have shown that, in mammals, the basi-cranial cartilage, both in the chordal and prechordal regions of the base of the skull, is developed as a single plate which extends from behind forward. In man, however, its posterior part shows an indication of being developed from two chondrifying centers which fuse rapidly in front and below. The anterior and posterior thirds of the cartilage surround the notochord, but its middle third lies on the dorsal aspect of the notochord, which in this region is placed between the cartilage and the wall of the pharynx. 20 FIG. 71 The same model as shown in Fig. 70 from the left side. Certain of the membrane bones of the right side are represented in yellow. (Hertwig.) ( See enlarged image ) Note 11. In the amphioxus the notochord persists and forms the only representative of a skeleton in that animal.

[ back ] Human Anatomy/Osteology/Skull - Wikibooks, open books for an open world Human Anatomy/Osteology/Skull Human skull (front) Human skull (side) The skull has evolved to be as lightweight as possible while offering the maximum amount of support and protection. In order to be light, the skull is made up by flat and irregular bones, and has hollow spaces such as the sinuses. It offers protection to the brain, eye balls, inner ears, and nasal passages. The human skull can be divided into two sections, the cranium and the face. In most people, the cranium is made up of 8 bones and the face is made up of 14. Often, the ossicles of the ear and the hyoid bone are counted as part of the skull, giving the normal human skull 29 bones (it should be noted that variations are not necessarily abnormal). Contents Cranium[ edit ] The cranium's main function is to protect the brain from trauma. The bones of the cranium are joined by sutures which look like wiggling lines across its surface. These joints fuse as a person matures.

There are four major sutures: Sagittal Suture- the joint between the two parietal bones. Coronal Suture- the joint between the frontal bone and the parietal bones. Squamous Suture- the joint between the parietal and temporal bones. Lambdoidal Suture- the joint between the parietal bones and the occipital bone. The last of these sutures to fuse is the coronal. Development[ edit ] The coronal suture eventually covers the infant's frontal fontanel, a membranous area between the bones of the skull. Fontanel allow the child's head to be more pliable during birth to allow for an easier delivery. They also allow for the accelerated growth of the human brain in the first years of life. In the newborn child, there are a total of 6 fontanels: Frontal- at the intersection of the parietal bones and the frontal bone. Occipital- at the intersection of the parietal bones and the occipital bone. Mastoid (2)- at the intersection of the parietal, occipital, and temporal bone on either side of the head.

Sphenoidal (2)- at the intersection of the parietal, temporal, frontal, and sphenoid bones on either side of the head. The occipital and sphenoidal fontanels (being the smaller of the six) close between the second and third months after birth. The mastoid usually fills in around a year after birth. And the frontal, which is the largest, generally takes between 18 to 24 months to close. Bones of the Cranium[ edit ] Base of the skull. Upper surface. (Anterior cranial fossa is the grayish area above the yellow and pink middle cranial fossa. The posterior cranial fossa is shown below the pink and yellow middle cranial fossa.) The calvaria, or the top hemisphere of the cranium is made up of the squamous bones, the superior part of the frontal bone, the parietal bones, and the superior part of the occipital bone. The base of the cranium consists of the ethmoid, sphenoid, and occipital bones. There are three distinct regions in the base of the cranium which can be seen from above with the calvaria removed.

These are called fossae and are named by their position with respect to the body: anterior, middle, and posterior fossae. The base of the cranium has several holes called foramina (singular, foramen) which allow blood vessels and nerves to enter and leave the cranium. Foramen and Canals[ edit ] The largest, most obvious foramen is located at the base of the occipital bone. It is named the foramen magnum. The spinal cord passes through this large opening and connects to the brain at the medulla oblongata. Just lateral to the foramen magnum are the much smaller hypoglossal canals which provide a passageway for the hypoglossal nerves. Beyond the hypoglossal canals, at the junction of the occipital bone with the temporal bones are the jugular foramina. These are all found in the posterior fossa. Osteology Introduction - Human Anatomy Total 206 The patellæ are included in this enumeration, but the smaller sesamoid bones are not reckoned. Bones are divisible into four classes: Long, Short, Flat, and Irregular.

Long Bones.The long bones are found in the limbs, and each consists of a body or shaft and two extremities. The body, or diaphysis is cylindrical, with a central cavity termed the medullary canal; the wall consists of dense, compact tissue of considerable thickness in the middle part of the body, but becoming thinner toward the extremities; within the medullary canal is some cancellous tissue, scanty in the middle of the body but greater in amount toward the ends. The extremities are generally expanded, for the purposes of articulation and to afford broad surfaces for muscular attachment. They are usually developed from separate centers of ossification termed epiphyses, and consist of cancellous tissue surrounded by thin compact bone. The medullary canal and the spaces in the cancellous tissue are filled with marrow. The long bones are not straight, but curved, the curve generally taking place in two planes, thus affording greater strength to the bone. The bones belonging to this class are: the clavicle, humerus, radius, ulna, femur, tibia, fibula, metacarpals, metatarsals, and phalanges.

Short Bones.Where a part of the skeleton is intended for strength and compactness combined with limited movement, it is constructed of a number of short bones, as in the carpus and tarsus. These consist of cancellous tissue covered by a thin crust of compact substance. The patellæ, together with the other sesamoid bones, are by some regarded as short bones. Flat Bones.Where the principal requirement is either extensive protection or the provision of broad surfaces for muscular attachment, the bones are expanded into broad, flat plates, as in the skull and the scapula. These bones are composed of two thin layers of compact tissue enclosing between them a variable quantity of cancellous tissue. In the cranial bones, the layers of compact tissue are familiarly known as the tables of the skull; the outer one is thick and tough; the inner is thin, dense, and brittle, and hence is termed the vitreous table. The intervening cancellous tissue is called the diploë, and this, in certain regions of the skull, becomes absorbed so as to leave spaces filled with air (air-sinuses) between the two tables.

The flat bones are: the occipital, parietal, frontal, nasal, lacrimal, vomer, scapula, os coxæ (hip bone), sternum, ribs, and, according to some, the patella. Irregular Bones.The irregular bones are such as, from their peculiar form, cannot be grouped under the preceding heads. They consist of cancellous tissue enclosed within a thin layer of compact bone. The irregular bones are: the vertebræ, sacrum, coccyx, temporal, sphenoid, ethmoid, zygomatic, maxilla, mandible, palatine, inferior nasal concha, and hyoid. Surfaces of Bones.If the surface of a bone be examined, certain eminences and depressions are seen. These eminences and depressions are of two kinds: articular and non-articular. Well-marked examples of articular eminences are found in the heads of the humerus and femur; and of articular depressions in the glenoid cavity of the scapula, and the acetabulum of the hip bone. Non-articular eminences are designated according to their form.

Thus, a broad, rough, uneven elevation is called a tuberosity, protuberance, or process, a small, rough prominence, a tubercle; a sharp, slender pointed eminence, a spine; a narrow, rough elevation, running some way along the surface, a ridge, crest, or line. Non-articular depressions are also of variable form, and are described as fossæ, pits, depressions, grooves, furrows, fissures, notches, etc. These non-articular eminences and depressions serve to increase the extent of surface for the attachment of ligaments and muscles, and are usually well-marked in proportion to the muscularity of the subject. A short perforation is called a foramen, a longer passage a canal. Development of the Skeleton The Skeleton.The skeleton is of mesodermal origin, and may be divided into (a) that of the trunk (axial skeleton), comprising the vertebral column, skull, ribs, and sternum, and (b) that of the limbs (appendicular skeleton). The Vertebral Column.The notochord (Fig.

19) is a temporary structure and forms a central axis, around which the segments of the vertebral column are developed. (* 11 It is derived from the entoderm, and consists of a rod of cells, which lies on the ventral aspect of the neural tube and reaches from the anterior end of the mid-brain to the extremity of the tail. On either side of it is a column of paraxial mesoderm which becomes subdivided into a number of more or less cubical segments, the primitive segments (Figs. 19 and 20). These are separated from one another by intersegmental septa and are arranged symmetrically on either side of the neural tube and notochord: to every segment a spinal nerve is distributed. At first each segment contains a central cavity, the myocl, but this is soon filled with a core of angular and spindle-shaped cells. The cells of the segment become differentiated into three groups, which form respectively the cutis-plate or dermatome, the muscle-plate or myotome, and the sclerotome (Fig. 64).

The cutis-plate is placed on the lateral and dorsal aspect of the myocl, and from it the true skin of the corresponding segment is derived; the muscle-plate is situated on the medial side of the cutis-plate and furnishes the muscles of the segment. The cells of the sclerotome are largely derived from those forming the core of the myocl, and lie next the notochord. Fusion of the individual sclerotomes in an antero-posterior direction soon takes place, and thus a continuous strand of cells, the sclerotogenous layer, is formed along the ventro-lateral aspects of the neural tube. The cells of this layer proliferate rapidly, and extending medialward surround the notochord; at the same time they grow backward on the lateral aspects of the neural tube and eventually surround it, and thus the notochord and neural tube are enveloped by a continuous sheath of mesoderm, which is termed the membranous vertebral column. In this mesoderm the original segments are still distinguishable, but each is now differentiated into two portions, an anterior, consisting of loosely arranged cells, and a posterior, of more condensed tissue (Fig.

65, A and B). Between the two portions the rudiment of the intervertebral fibrocartilage is laid down (Fig. 65, C). Cells from the posterior mass grow into the intervals between the myotomes (Fig. 65, B and C) of the corresponding and succeeding segments, and extend both dorsally and ventrally; the dorsal extensions surround the neural tube and represent the future vertebral arch, while the ventral extend into the body-wall as the costal processes. The hinder part of the posterior mass joins the anterior mass of the succeeding segment to form the vertebral body. Each vertebral body is therefore a composite of two segments, being formed from the posterior portion of one segment and the anterior part of that immediately behind it. The vertebral and costal arches are derivatives of the posterior part of the segment in front of the intersegmental septum with which they are associated. FIG. 65 Scheme showing the manner in which each vertebral centrum is developed from portions of two adjacent segments. This stage is succeeded by that of the cartilaginous vertebral column.

In the fourth week two cartilaginous centers make their appearance, one on either side of the notochord; these extend around the notochord and form the body of the cartilaginous vertebra. A second pair of cartilaginous foci appear in the lateral parts of the vertebral bow, and grow backward on either side of the neural tube to form the cartilaginous vertebral arch, and a separate cartilaginous center appears for each costal process. By the eighth week the cartilaginous arch has fused with the body, and in the fourth month the two halves of the arch are joined on the dorsal aspect of the neural tube. The spinous process is developed from the junction of the two halves of the vertebral arch. The transverse process grows out from the vertebral arch behind the costal process. In the upper cervical vertebræ a band of mesodermal tissue connects the ends of the vertebral arches across the ventral surfaces of the intervertebral fibrocartilages. This is termed the hypochordal bar or brace; in all except the first it is transitory and disappears by fusing with the fibrocartilages.

In the atlas, however, the entire bow persists and undergoes chondrification; it develops into the anterior arch of the bone, while the cartilage representing the body of the atlas forms the dens or odontoid process which fuses with the body of the second cervical vertebra. FIG. 66 Sagittal section through an intervertebral fibrocartilage and adjacent parts of two vertebræ of an advanced sheeps embryo. (Kölliker.) The portions of the notochord which are surrounded by the bodies of the vertebræ atrophy, and ultimately disappear, while those which lie in the centers of the intervertebral fibrocartilages undergo enlargement, and persist throughout life as the central nucleus pulposus of the fibrocartilages (Fig. 66). The Ribs.The ribs are formed from the ventral or costal processes of the primitive vertebral bows, the processes extending between the muscle-plates. In the thoracic region of the vertebral column the costal processes grow lateralward to form a series of arches, the primitive costal arches. As already described, the transverse process grows out behind the vertebral end of each arch.

It is at first connected to the costal process by continuous mesoderm, but this becomes differentiated later to form the costotransverse ligament; between the costal process and the tip of the transverse process the costotransverse joint is formed by absorption. The costal process becomes separated from the vertebral bow by the development of the costocentral joint. In the cervical vertebr (Fig. 67) the transverse process forms the posterior boundary of the foramen transversarium, while the costal process corresponding to the head and neck of the rib fuses with the body of the vertebra, and forms the antero-lateral boundary of the foramen. The distal portions of the primitive costal arches remain undeveloped; occasionally the arch of the seventh cervical vertebra undergoes greater development, and by the formation of costovertebral joints is separated off as a rib. In the lumbar region the distal portions of the primitive costal arches fail; the proximal portions fuse with the transverse processes to form the transverse processes of descriptive anatomy. Occasionally a movable rib is developed in connection with the first lumbar vertebra.

In the sacral region costal processes are developed only in connection with the upper three, or it may be four, vertebræ the processes of adjacent segments fuse with one another to form the lateral parts of the sacrum. The coccygeal vertebr are devoid of costal processes. FIG. 67 Diagrams showing the portions of the adult vertebræ derived respectively from the bodies, vertebral arches, and costal processes of the embryonic vertebræ. The bodies are represented in yellow, the vertebral arches in red, and the costal processes in blue. The Sternum.The ventral ends of the ribs become united to one another by a longitudinal bar termed the sternal plate, and opposite the first seven pairs of ribs these sternal plates fuse in the middle line to form the manubrium and body of the sternum. The xiphoid process is formed by a backward extension of the sternal plates.

The Skull.Up to a certain stage the development of the skull corresponds with that of the vertebral column; but it is modified later in association with the expansion of the brain-vesicles, the formation of the organs of smell, sight, and hearing, and the development of the mouth and pharynx. The notochord extends as far forward as the anterior end of the mid-brain, and becomes partly surrounded by mesoderm (Fig. 68). The posterior part of this mesodermal investment corresponds with the basilar part of the occipital bone, and shows a subdivision into four segments, which are separated by the roots of the hypoglossal nerve. The mesoderm then extends over the brain-vesicles, and thus the entire brain is enclosed by a mesodermal investment, which is termed the membranous cranium. From the inner layer of this the bones of the skull and the membranes of the brain are developed; from the outer layer the muscles, bloodvessels, true skin, and subcutaneous tissues of the scalp.

In the shark and dog-fish this membranous cranium undergoes complete chondrification, and forms the cartilaginous skull or chondrocranium of these animals. In mammals, on the other hand, the process of chondrification is limited to the base of the skullthe roof and sides being covered in by membrane. Thus the bones of the base of the skull are preceded by cartilage, those of the roof and sides by membrane. The posterior part of the base of the skull is developed around the notochord, and exhibits a segmented condition analogous to that of the vertebral column, while the anterior part arises in front of the notochord and shows no regular segmentation. The base of the skull may therefore be divided into (a) a chordal or vertebral, and (b) a prechordal or prevertebral portion. FIG. 68 Sagittal section of cephalic end of notochord. (Keibel.) FIG. 69 Diagrams of the cartilaginous cranium.

(Wiedersheim.) In the lower vertebrates two pairs of cartilages are developed, viz., a pair of parachordal cartilages, one on either side of the notochord; and a pair of prechordal cartilages, the trabeculæ cranii, in front of the notochord (Fig. 66). The parachordal cartilages (Fig. 69) unite to form a basilar plate, from which the cartilaginous part of the occipital bone and the basi-sphenoid are developed. On the lateral aspects of the parachordal cartilages the auditory vesicles are situated, and the mesoderm enclosing them is soon converted into cartilage, forming the cartilaginous ear-capsules. These cartilaginous ear-capsules, which are of an oval shape, fuse with the sides of the basilar plate, and from them arise the petrous and mastoid portions of the temporal bones. The trabeculæ cranii (Fig.

69) are two curved bars of cartilage which embrace the hypophysis cerebri; their posterior ends soon unite with the basilar plate, while their anterior ends join to form the ethmoidal plate, which extends forward between the fore-brain and the olfactory pits. Later the trabeculæ meet and fuse below the hypophysis, forming the floor of the fossa hypophyseos and so cutting off the anterior lobe of the hypophysis from the stomodeum. The median part of the ethmoidal plate forms the bony and cartilaginous parts of the nasal septum. From the lateral margins of the trabeculæ cranii three processes grow out on either side. The anterior forms the ethmoidal labyrinth and the lateral and alar cartilages of the nose; the middle gives rise to the small wing of the sphenoid, while from the posterior the great wing and lateral pterygoid plate of the sphenoid are developed (Figs. 70, 71). The bones of the vault are of membranous formation, and are termed dermal or covering bones.

They are partly developed from the mesoderm of the membranous cranium, and partly from that which lies outside the entoderm of the foregut. They comprise the upper part of the occipital squama (interparietal), the squamæ and tympanic parts of the temporals, the parietals, the frontal, the vomer, the medial pterygoid plates, and the bones of the face. Some of them remain distinct throughout life, e.g., parietal and frontal, while others join with the bones of the chondrocranium, e.g., interparietal, squamæ of temporals, and medial pterygoid plates. FIG. 70 Model of the chondrocranium of a human embryo, 8 cm. long. (Hertwig.) The membrane bones are not represented. Recent observations have shown that, in mammals, the basi-cranial cartilage, both in the chordal and prechordal regions of the base of the skull, is developed as a single plate which extends from behind forward.

In man, however, its posterior part shows an indication of being developed from two chondrifying centers which fuse rapidly in front and below. The anterior and posterior thirds of the cartilage surround the notochord, but its middle third lies on the dorsal aspect of the notochord, which in this region is placed between the cartilage and the wall of the pharynx. FIG. 71 The same model as shown in Fig. 70 from the left side. Certain of the membrane bones of the right side are represented in yellow. (Hertwig.) Note 11. In the amphioxus the notochord persists and forms the only representative of a skeleton in that animal. [ back ] Osteology Study Resources Sign up Osteology Study Resources Need some extra help with Osteology? Browse notes, questions, homework, exams and much more, covering Osteology and many other concepts. School: LSU Course: ANTH 2015 Anthropology 2015: Human Osteology for Archaeologists Heather McKillop. Human Osteology. field id of bones: age at death. sex. health status (while alive). # bones?

206 adult skeleton; 300+ newborn skeleton. babies are born with more bones whi... 3 Pages osteology Flashcards - Cram.com osteology Flashcards OCPM lower anatomy quiz 8 2008. Subjects: Winter 2010 Gross Anatomy - Head Osteology. Subjects: Osteology Qs in preparation for first gross anatomy quiz. Subjects: Introduction and directional terms motions of the body projections and parts depressions. Subjects: UKC palaeopathology course test flash cards. Subjects: Gross - Osteology and Muscles of the Proximal Thoracic Limb - MT1. Subjects: Skeletal system True or False, Blank answer (Questions from Schaum's human anatomy and physiology book). Subjects: This set of flash cards include topics about: • Anatomical Directions • Functions of Bone • Scientific Method • Bone Growt.... Subjects: II. Osteology. 4b. The Ribs. Gray, Henry. 1918. Anatomy of the Human Body. Henry Gray (18211865). Anatomy of the Human Body. 1918.

(Costæ) The ribs are elastic arches of bone, which form a large part of the thoracic skeleton. They are twelve in number on either side; but this number may be increased by the development of a cervical or lumbar rib, or may be diminished to eleven. The first seven are connected behind with the vertebral column, and in front, through the intervention of the costal cartilages, with the sternum (Fig. 115) ; they are called true or vertebro-sternal ribs. 21 The remaining five are false ribs; of these, the first three have their cartilages attached to the cartilage of the rib above (vertebro-chondral): the last two are free at their anterior extremities and are termed floating or vertebral ribs. The ribs vary in their direction, the upper ones being less oblique than the lower; the obliquity reaches its maximum at the ninth rib, and gradually decreases from that rib to the twelfth. The ribs are situated one below the other in such a manner that spaces called intercostal spaces are left between them.

The length of each space corresponds to that of the adjacent ribs and their cartilages; the breadth is greater in front than behind, and between the upper than the lower ribs. The ribs increase in length from the first to the seventh, below which they diminish to the twelfth. In breadth they decrease from above downward; in the upper ten the greatest breadth is at the sternal extremity. 1 Common Characteristics of the Ribs ( Figs. 122, 123 ).A rib from the middle of the series should be taken in order to study the common characteristics of these bones. 4 The head is marked by a kidney-shaped articular surface, divided by a horizontal crest into two facets for articulation with the depression formed on the bodies of two adjacent thoracic vertebræ; the upper facet is the smaller; to the crest is attached the interarticular ligament. 5 The neck is the flattened portion which extends lateralward from the head; it is about 2.5 cm. long, and is placed in front of the transverse process of the lower of the two vertebræ with which the head articulates.

Its anterior surface is flat and smooth, its posterior rough for the attachment of the ligament of the neck, and perforated by numerous foramina. Of its two borders the superior presents a rough crest (crista colli cost) for the attachment of the anterior costotransverse ligament; its inferior border is rounded. On the posterior surface at the junction of the neck and body, and nearer the lower than the upper border, is an eminencethe tubercle; it consists of an articular and a non-articular portion. The articular portion, the lower and more medial of the two, presents a small, oval surface for articulation with the end of the transverse process of the lower of the two vertebræ to which the head is connected. The non-articular portion is a rough elevation, and affords attachment to the ligament of the tubercle. The tubercle is much more prominent in the upper than in the lower ribs. FIG. 122 A central rib of the left side. Inferior aspect.

( See enlarged image ) Body.The body or shaft is thin and flat, with two surfaces, an external and an internal; and two borders, a superior and an inferior. The external surface is convex, smooth, and marked, a little in front of the tubercle, by a prominent line, directed downward and lateralward; this gives attachment to a tendon of the Iliocostalis, and is called the angle. At this point the rib is bent in two directions, and at the same time twisted on its long axis. If the rib be laid upon its lower border, the portion of the body in front of the angle rests upon this border, while the portion behind the angle is bent medialward and at the same time tilted upward; as the result of the twisting, the external surface, behind the angle, looks downward, and in front of the angle, slightly upward. The distance between the angle and the tubercle is progressively greater from the second to the tenth ribs. The portion between the angle and the tubercle is rounded, rough, and irregular, and serves for the attachment of the Longissimus dorsi.

The internal surface is concave, smooth, directed a little upward behind the angle, a little downward in front of it, and is marked by a ridge which commences at the lower extremity of the head; this ridge is strongly marked as far as the angle, and gradually becomes lost at the junction of the anterior and middle thirds of the bone. Between it and the inferior border is a groove, the costal groove, for the intercostal vessels and nerve. At the back part of the bone, this groove belongs to the inferior border, but just in front of the angle, where it is deepest and broadest, it is on the internal surface. The superior edge of the groove is rounded and serves for the attachment of an Intercostalis internus; the inferior edge corresponds to the lower margin of the rib, and gives attachment to an Intercostalis externus. Within the groove are seen the orifices of numerous small foramina for nutrient vessels which traverse the shaft obliquely from before backward. The superior border, thick and rounded, is marked by an external and an internal lip, more distinct behind than in front, which serve for the attachment of Intercostales externus and internus.

The inferior border is thin, and has attached to it an Intercostalis externus. 7 Anterior Extremity.The anterior or sternal extremity is flattened, and presents a porous, oval, concave depression, into which the costal cartilage is received. 8 Peculiar Ribs.The first, second, tenth, eleventh, and twelfth ribs present certain variations from the common characteristics described above, and require special consideration. FIG. 123 A central rib of the left side, viewed from behind. ( See enlarged image ) First Rib.The first rib (Fig. 124) is the most curved and usually the shortest of all the ribs; it is broad and flat, its surfaces looking upward and downward, and its borders inward and outward. The head is small, rounded, and possesses only a single articular facet, for articulation with the body of the first thoracic vertebra. The neck is narrow and rounded. The tubercle, thick and prominent, is placed on the outer border. There is no angle, but at the tubercle the rib is slightly bent, with the convexity upward, so that the head of the bone is directed downward.

The upper surface of the body is marked by two shallow grooves, separated from each other by a slight ridge prolonged internally into a tubercle, the scalene tubercle, for the attachment of the Scalenus anterior; the anterior groove transmits the subclavian vein, the posterior the subclavian artery and the lowest trunk of the brachial plexus. 22 Behind the posterior groove is a rough area for the attachment of the Scalenus medius. The under surface is smooth, and destitute of a costal groove. The outer border is convex, thick, and rounded, and at its posterior part gives attachment to the first digitation of the Serratus anterior; the inner border is concave, thin, and sharp, and marked about its center by the scalene tubercle. The anterior extremity is larger and thicker than that of any of the other ribs. Second Rib.The second rib (Fig. 125) is much longer than the first, but has a very similar curvature. The non-articular portion of the tubercle is occasionally only feebly marked. The angle is slight, and situated close to the tubercle.

The body is not twisted, so that both ends touch any plane surface upon which it may be laid; but there is a bend, with its convexity upward, similar to, though smaller than that found in the first rib. The body is not flattened horizontally like that of the first rib. Its external surface is convex, and looks upward and a little outward; near the middle of it is a rough eminence for the origin of the lower part of the first and the whole of the second digitation of the Serratus anterior; behind and above this is attached the Scalenus posterior. The internal surface, smooth, and concave, is directed downward and a little inward: on its posterior part there is a short costal groove. FIG. 124 Peculiar ribs. ( See enlarged image ) FIG. 125 Peculiar ribs. ( See enlarged image ) FIG. 126 Peculiar ribs. ( See enlarged image ) FIG. 127 Peculiar ribs. ( See enlarged image ) FIG. 128 Peculiar ribs.

( See enlarged image ) 12 Eleventh and Twelfth Ribs.The eleventh and twelfth ribs ( Figs. 127 and 128 ) have each a single articular facet on the head, which is of rather large size; they have no necks or tubercles, and are pointed at their anterior ends. The eleventh has a slight angle and a shallow costal groove. The twelfth has neither; it is much shorter than the eleventh, and its head is inclined slightly downward. Sometimes the twelfth rib is even shorter than the first. Structure.The ribs consist of highly vascular cancellous tissue, enclosed in a thin layer of compact bone. 14 Ossification.Each rib, with the exception of the last two, is ossified from four centers; a primary center for the body, and three epiphysial centers, one for the head and one each for the articular and non-articular parts of the tubercle. The eleventh and twelfth ribs have each only two centers, those for the tubercles being wanting.

Ossification begins near the angle toward the end of the second month of fetal life, and is seen first in the sixth and seventh ribs. The epiphyses for the head and tubercle make their appearance between the sixteenth and twentieth years, and are united to the body about the twenty-fifth year. Fawcett 23 states that in all probability there is usually no epiphysis on the non-articular part of the tuberosity below the sixth or seventh rib.

Question: Osteology is the study of which part of the human body?
Answer: Bones